Further to my earlier post (briefed by a member of the Leader's office) this statement has just been released by a spokesman for the Tory Treasury team:
CCHQ is saying that the IHT commitment is consistent with the party's overall commitment to social justice because it is funded by taxation of rich non-doms.
"So far as I am concerned, we are fully committed to raising the threshold for Inheritance Tax in the first parliament of a Conservative government, as George Osborne has promised. This measure will appear in the manifesto and I support it. We also all agree that George Osborne cannot write his first Budget until we have seen what we have inherited. I cannot see any significant difference between what I have said and what my colleagues have said."